As a method of mounting a semiconductor element, a film carrier system has hitherto been employed and for inner bonding of the leads on the film carrier and the electrodes of a semiconductor element, bumps for connection have been utilized.
Hitherto, as such a bonding method, a method of using a so-called anisotropic electrically conductive film is proposed. Practically, an insulating film in which electrically conductive particles such as the particles of carbon black, graphite, nickel, copper, silver, etc., are dispersed in the oriented state to the thickness direction has been used. However, when the orientation of the dispersed conductive particles is insufficient, the electric connection between the electrode portion of a semiconductor element and the lead portion of a film carrier becomes uncertain, which causes a problem in the point of connection reliability.
On the other hand, a method of forming bumps at the lead side of a film carrier and directly connecting the lead portions to the electrode portion of a semiconductor element is proposed. However, in the method, when wiring of a semiconductor becomes a fine pitch or high density, it becomes difficult to form the wiring or the bumps corresponding to the technique on a film carrier and also the connecting operation must be carried out with the greatest care.
Furthermore, when a film carrier having a wiring circuit and lead portions is used on the surface of a conventional insulating film, usually the area of outer bonding becomes larger than the area of inner bonding, whereby the final mounting area becomes larger than the size (area) of a semiconductor element and thus when hereafter, a small sized device is required, there is a possibility that the foregoing method cannot sufficiently correspond to the requirement.